MSM765 Integrated Controller DHCP relay agent issue

[lucky101]

Hi All,

We have two separate internet service providers (lets say {A} internal and {B} guest). We have two ISPs, so we can separate the internal and guest network completely.

{A} internet service provider is connected to our internal firewall and from there to our core switch. Lan port (L2) on MSM765 is untagged on the default vlan on the switch as well.

{B} internet service provider is connected to a small linksys router which gets connected to the core switch and is part of another vlan. Internet port (L1) on MSM765 is untagged on that vlan.

Since we already have a DHCP server on internal network, there is no point in creating another dhcp on the controller as it is stated on the manual. We went ahead to set up the Dhcp relay for the guest network.

Lets say the small linksys rounter ip is 192.168.1.1/24 and the internet port on msm765 is 192.168.1.2/24. When we enable dhcp relay agent, we have check mark on "client data tunnel" and nothing on LAN port. We enter 192.168.1.1 as Primary server address but the checkmark for "extend vsc egress subnet to vsc ingress subnet is greyed out". DHCP on the linksys router is enabled.

When we go to the guest vsc, we place check mark on Dhcp relay agent and enter the ip addres 192.168.1.1 as primary dhcp. The "subnet selection" gets address "192.168.1.1" and the mask "255.255.255.0.

The default route is set to internet port with ip 192.168.1.1 with metric as 1.

When the clients connect to the controller they get the ip addresses but aren't able to get to the internet. The get yellow triangle with exclamation mark.

Can anyone please help me out here? I need this asap.

Thanks

[JesseR]

You will need to enable the "extend VSC egress subnet to VSC ingress subnet" .. It's grayed out for you because of a BUG, but you can still trick it so it becomes selectable. It's 11pm at night, so I'm a bit tired and can't remember the sequence you need to go through to get that option so its NOT grayed out...

Furthermore, on the guest VSC, enable the DHCP relay option, and make sure you select "Forward to egress interface". You will NOT have to put an IP address/subnet in when doing that.

Getting those two things fixed will allow DHCP to work from the external DHCP server to the guest clients. I have that on 30+ MSM controllers without issue.

ON a side note, IF you external DHCP server is on a different network than your MSM (in this case, yours ISN'T, but...) you will need to use an IP helper on the VLAN.

[lucky101]

Hi Jesse,

Thank you so much for your help. We have to uncheck NAT on Internet port which gave us the ability to check mark "Extend VSC egress subnet to VSC ingress subnet". I also had to give a dummy ip address as primary server address under server in DHCP relay agent/Address allocation tab. We didn't had to add the exact ip address of the dhcp server.

Lastly as you said, on guest wifi we selected "forward to egress interface" under dhcp relay agent. Thank you again for all of your help.

[Intermedium]

Hello guys,

I just had the exact same issue, and I'm here to say that the sollution worked beautifully for us. Spent a long time trying to figure out why the DHCP scenario could't work.

Appreciate your help.